This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We plan to use transmission X-ray microscopy to investigate morphologic changes in cell nuclei caused by changes in hydration. Do nucleosomes and interchromatin space sizes change in response to dehydration and rehydration because of B-DNA to A-DNA to B-DNA conformational change? We will endeavor to test two hypotheses: 1) The nucleosomes become smaller in response to dehydration and returns to full size upon rehydration because of the B-DNA to A-DNA to B-DNA conformational change. 2) The interchromatin space becomes smaller in response to dehydration and increases during rehydration in response to DNA conformational change.